linux-kernel - Re: [PATCH v3] x86/cpuid: expose AVX512_4VNNIW and AVX512

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Message-ID: <ecdc20d5-e5c2-cab7-2973-39c811cac42c@redhat.com>
Date:   Fri, 4 Nov 2016 15:53:02 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Borislav Petkov <bp@...en8.de>, He Chen <he.chen@...ux.intel.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org, x86@...nel.org,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>,
        Luwei Kang <luwei.kang@...el.com>,
        Piotr Luc <Piotr.Luc@...el.com>
Subject: Re: [PATCH v3] x86/cpuid: expose AVX512_4VNNIW and AVX512_4FMAPS
 features to kvm guest



On 04/11/2016 11:52, Borislav Petkov wrote:
> Please CC me on your future submissions, thanks.
> 
> On Fri, Nov 04, 2016 at 03:07:19PM +0800, He Chen wrote:
>> The spec can be found in Intel Software Developer Manual or in
>> Instruction Set Extensions Programming Reference.
> 
> This commit message is completely useless. Write commit messages in
> the way as if you're explaining to another person *why* this change is
> needed and that other person doesn't have an idea what you're doing.
> 
>> Signed-off-by: Luwei Kang <luwei.kang@...el.com>
>> Signed-off-by: He Chen <he.chen@...ux.intel.com>
> 
> This SOB chain means what exactly?
> 
>> ---
>> Changes in v3:
>> * add a helper in scattered.c to get scattered leaf.
> 
> The modification to scattered et al without the kvm use should be a
> separate patch.

With no usage?  Sounds like a good use of Acked-by. :)

>> +u32 get_scattered_cpuid_leaf(unsigned int level, unsigned int sub_leaf,
>> +			     enum cpuid_regs_idx reg)
> 
> Align arguments on the opening brace.

They are aligned.

Paolo

>> +{
>> +	u32 cpuid_val = 0;
>> +	const struct cpuid_bit *cb;
> 
> 
> Please sort function local variables declaration in a reverse christmas
> tree order:
> 
> 	<type> longest_variable_name;
> 	<type> shorter_var_name;
> 	<type> even_shorter;
> 	<type> i;
> 
>> +
>> +	for (cb = cpuid_bits; cb->feature; cb++) {
>> +
>> +		if (level > cb->level)
>> +			continue;
>> +
>> +		if (level < cb->level)
>> +			break;
>> +
>> +		if (reg == cb->reg && sub_leaf == cb->sub_leaf) {
>> +			if (cpu_has(&boot_cpu_data, cb->feature))
>> +				cpuid_val |= BIT(cb->bit);
>> +		}
>> +	}
>> +
>> +	return cpuid_val;
>> +}
>